Gut Microbiota: The Brain Peacekeeper

Analysis of the effects of nanosilver on bacterial community in the intestinal fluid of silkworms using high-throughput sequencing

Nanosilver is an environment-friendly, harmless alternative of traditional disinfectants which can be potentially applied in the sericulture industry. However, the effects of nanosilver on the intestinal bacterial community of the silkworms (Bombyx mori L.) are unclear. In this study, Illumina MiSeq high-throughput sequencing technology was used to assess the intestinal bacterial community in both male and female silkworms while treated with different concentrations of nanosilver. We found that nanosilver significantly influenced the composition of silkworm intestinal bacterial community on the different taxonomic levels. Most conspicuously, the abundance of Firmicutes was increased by the treatment of 20 mg L-1 nanosilver but decreased by that of 100 mg L-1 nanosilver at the phylum level. The same trend was observed in Bacilli at the class level and in Enterococcus at the genus level. In some extreme cases, application of nanosilver eliminated the bacterium, e.g., Brevibacillus, but increased the population of several other bacteria in the host intestine, such as Blautia, Terrisporobacter, Faecalibacterium, and some bacteria could only be found in nanosilver treatment groups, e.g., Dialister. In addition, although nanosilver generally showed negative effects on the cocooning rate in a dose-dependent manner, we found that 20 mg L-1 nanosilver treatment significantly increased the body weight of silkworms and did not show negative effects on the survival rate. These results indicated that the intestinal bacteria community of silkworm larvae was significantly changed after nanosilver treatment which might consequently influence host growth and development.

The Microbiome and the Gut-Liver-Brain Axis for Central Nervous System Clinical Pharmacology: Challenges in Specifying and Integrating In Vitro and In Silico Models

The complexity of integrating microbiota into clinical pharmacology, environmental toxicology, and opioid studies arises from bidirectional and multiscale interactions between humans and their many microbiota, notably those of the gut. Hosts and each microbiota are governed by distinct central dogmas, with genetics influencing transcriptomics, proteomics, and metabolomics. Each microbiota's metabolome differentially modulates its own and the host's multi‐omics. Exogenous compounds (e.g., drugs and toxins), often affect host multi‐omics differently than microbiota multi‐omics, shifting the balance between drug efficacy and toxicity. The complexity of the host‐microbiota connection has been informed by current methods of in vitro bacterial cultures and in vivo mouse models, but they fail to elucidate mechanistic details. Together, in vitro organ‐on‐chip microphysiological models, multi‐omics, and in silico computational models have the potential to supplement the established methods to help clinical pharmacologists and environmental toxicologists unravel the myriad of connections between the gut microbiota and host health and disease.

Altered circadian clock as a novel therapeutic target for constant darkness-induced insulin resistance and hyperandrogenism of polycystic ovary syndrome

The mechanisms underlying metabolic and reproductive dysfunction caused by arrhythmic circadian clock and their involvement in polycystic ovary syndrome (PCOS) are not understood. Here, we addressed this issue using rats with constant light or darkness exposure for 8 weeks and human leukocytes and serum of PCOS and non-PCOS patients. Additionally, we utilized HepG2 cells and KGN cells to verify the molecular mechanisms. The arrhythmic expressions of circadian clock genes due to constant darkness induced the metabolic and reproductive hallmarks of PCOS in rats. After exposure to constant darkness, decreased brain and muscle ARNT-like protein 1 (BMAL1) promoted insulin resistance via glucose transporter 4 (GLUT4), and decreased period (PER) 1 and PER2 promoted androgen excess via insulin-like growth factor-binding protein 4 (IGFBP4) and sex hormone binding globulin (SHBG) in the liver. Hyperinsulinemia and hyperandrogenism shared a bidirectional link promoting aberrant expression of circadian genes and inducing apoptosis of ovarian granulosa cells. Notably, the altered expressions of circadian clock genes in darkness-treated rats matched those of PCOS patients. Furthermore, melatonin treatment relieved the hyperinsulinemia and hyperandrogenism of darkness-treated rats via BMAL1, PER1, and PER2. Restoring normal light/dark exposure for 2 weeks reversed these conditions via BMAL1. In conclusion, our findings elucidated the critical function of circadian clock genes, especially BMAL1, PER1, and PER2 in PCOS, which might aid the development of feasible preventive and therapeutic strategies for PCOS in women with biorhythm disorder.

The importance of diet-related effects of the antibiotic ciprofloxacin on the leaf-shredding invertebrate Gammarus fossarum (Crustacea; Amphipoda)

Antibiotics may constitute a risk for aquatic detritivorous macroinvertebrates (i.e., shredders) via waterborne and dietary antibiotic exposure. In addition, antibiotics can alter the food quality for shredders mediated by shifts in leaf-associated decomposer (i.e., aquatic fungi and bacteria) communities. However, little is known about the relative importance of the waterborne and dietary effect pathway. Therefore, we followed a tiered testing approach aimed at assessing the relative importance of these effect pathways. We employed the antibiotic ciprofloxacin (CIP) and the shredder Gammarus fossarum as model stressor and test species, respectively. In a first step, we assessed the short-term waterborne toxicity of CIP using survival and leaf consumption of G. fossarum as response variables. Alterations in the leaf-associated decomposer community, which may be reflected by their palatability, were assessed using food choice assays. Finally, we conducted a 2 × 2-factorial experiment over 24 days assessing the pathways individually and combined using energy processing (i.e., leaf consumption and feces production), growth and energy storage (i.e., neutral lipid fatty acids) as variables. Short term waterborne exposure indicated low toxicity with LC₅₀ and EC₅₀ values of 13.6 and 6.4 mg CIP/L, respectively. At the same time, shredders did not prefer any leaf material during the food choice assay. However, the fungal community was significantly affected in the highest CIP-treatments (0.5 and 2.5 mg/L) suggesting an altered food quality for shredders. This assumption is supported by the results of the long-term assay. At 0.5 mg CIP/L, gammarids' leaf consumption, growth and energy storage were increased when subjected via the dietary pathway, which was linked to changes in the leaf-associated microbial community. Our data highlight the importance of dietary effect pathways for effects on shredders, potentially impacting energy dynamics in detritus-based stream ecosystems.

Tryptophan Metabolism: A Link Between the Gut Microbiota and Brain

The gut-brain axis (GBA) is a bilateral communication network between the gastrointestinal (GI) tract and the central nervous system. The essential amino acid tryptophan contributes to the normal growth and health of both animals and humans and, importantly, exerts modulatory functions at multiple levels of the GBA. Tryptophan is the sole precursor of serotonin, which is a key monoamine neurotransmitter participating in the modulation of central neurotransmission and enteric physiological function. In addition, tryptophan can be metabolized into kynurenine, tryptamine, and indole, thereby modulating neuroendocrine and intestinal immune responses. The gut microbial influence on tryptophan metabolism emerges as an important driving force in modulating tryptophan metabolism. Here, we focus on the potential role of tryptophan metabolism in the modulation of brain function by the gut microbiota. We start by outlining existing knowledge on tryptophan metabolism, including serotonin synthesis and degradation pathways of the host, and summarize recent advances in demonstrating the influence of the gut microbiota on tryptophan metabolism. The latest evidence revealing those mechanisms by which the gut microbiota modulates tryptophan metabolism, with subsequent effects on brain function, is reviewed. Finally, the potential modulation of intestinal tryptophan metabolism as a therapeutic option for brain and GI functional disorders is also discussed.

Traditional Chinese Medicine in Emergency Treatment Mechanism and Application

Traditional Chinese medicine has usually been recognized to be efficacious to treat chronic diseases from the western point-of-view. However, there is a long history in China of applying traditional Chinese medicine in many acute and urgent medical conditions. In this review, selected methods documented in traditional Chinese medicine including blowing air to ear, nose insufflating therapy, acupuncture and moxibustion were presented as the common practices to promote consciousness recovery from coma. We aimed to explore the mechanism of these four methods with current scientific evidence, further discuss the potential of traditional Chinese medicine to be applied in emergency medicine and provide a path forward to more rigorously validate these procedures. The development of the integrated traditional Chinese medicine and western medicines provides a new therapeutic direction for the new first-aid treatment.

A comparison of nonlethal sampling methods for amphibian gut microbiome analyses

Noninvasive sampling methods for studying intestinal microbiomes are widely applied in studies of endangered species and in those conducting temporal monitoring during manipulative experiments. Although existing studies show that noninvasive sampling methods among different taxa vary in their accuracy, no studies have yet been published comparing nonlethal sampling methods in adult amphibians. In this study, we compare microbiomes from two noninvasive sample types (faeces and cloacal swabs) to that of the large intestine in adult cane toads, Rhinella marina. We use 16S rRNA gene sequencing to investigate how microbial communities change along the digestive tract and which nonlethal sampling method better represents large intestinal microbiota. We found that cane toads' intestinal microbiota was dominated by Bacteroidetes, Proteobacteria and Firmicutes and, interestingly, we also saw a high proportion of Fusobacteria, which has previously been associated with marine species and changes in frog immunity. The large and small intestine of cane toads had a similar microbial composition, but the large intestine showed higher diversity. Our results indicate that cloacal swabs were more similar to large intestine samples than were faecal samples, and small intestine samples were significantly different from both nonlethal sample types. Our study provides valuable information for future investigations of the cane toad gut microbiome and validates the use of cloacal swabs as a nonlethal method to study changes in the large intestine microbiome. These data provide insights for future studies requiring nonlethal sampling of amphibian gut microbiota.

The role of the brain-gut-microbiota axis in psychology: The importance of considering gut microbiota in the development, perpetuation, and treatment of psychological disorders

INTRODUCTION

The prevalence of psychological disorders remains stable despite steady increases in pharmacological treatments suggesting the need for auxiliary treatment options. Consideration of the brain-gut-microbiota axis (BGMA) has made inroads into reconceptualizing psychological illness from a more holistic perspective. While our understanding of the precise role of gut microbiota (GM) in psychological illness is in its infancy, it represents an attractive target for novel interventions.

METHOD

An extensive review of relevant literature was undertaken.

RESULTS

Gut microbiota are proposed to directly and indirectly influence mood, cognition, and behavior which are key components of mental health. This paper outlines how GM may be implicated in psychological disorders from etiology through to treatment and prevention using the Four P model of case formulation.

CONCLUSION

Moving forward, integration of GM into the conceptualization and treatment of psychological illness will require the discipline of psychology to undergo a significant paradigm shift. While the importance of the GM in psychological well-being must be respected, it is not proposed to be a panacea, but instead, an additional arm to a multidisciplinary approach to treatment and prevention.

Ex Vivo Analysis of Tryptophan Metabolism Using 19F NMR

Tryptophan, an essential amino acid, is metabolized into a variety of small molecules capable of impacting human physiology, and aberrant tryptophan metabolism has been linked to a number of diseases. There are three principal routes by which tryptophan is degraded, and thus methods for measuring metabolic flux through these pathways can be used to understand the factors that perturb tryptophan metabolism and potentially to measure disease biomarkers. Here, we describe a method utilizing 6-fluorotryptophan as a probe for detecting tryptophan metabolites in ex vivo tissue samples via ¹⁹F nuclear magnetic resonance. As a proof of concept, we demonstrate that 6-fluorotryptophan can be used to measure changes in tryptophan metabolism resulting from antibiotic-induced changes in gut microbiota composition. Taken together, we describe a general strategy for monitoring amino acid metabolism using ¹⁹F nuclear magnetic resonance that is operationally simple and does not require chromatographic separation of metabolites.

The microbiome: implications for perioperative and critical care

PURPOSE OF REVIEW

The host-microbiota relationship is integral in human health and can be rapidly disrupted in ways that may contribute to poor recovery from surgery or acute illness. We review key studies by organ system to understand the effect of perioperative and critical illness stress on the microbiota. Throughout the review, our focus is on potential interventions that may be mediated by the microbiome.

RECENT FINDINGS

Although any perioperative intervention can have a profound impact on the gut microbiota, it is less clear how such changes translate into altered health outcomes. Preoperative stress (anxiety, lack of sleep, fasting), intraoperative stress (surgery itself, volatile anesthetics, perioperative antibiotics, blood transfusions), and postoperative stress (sepsis, surgical site infections, acute respiratory distress syndrome, catecholamines, antibiotics, opioids, proton pump inhibitors) have all been associated with alterations of the commensal microflora. These factors (e.g. administration of antibiotics or opioids) can create a favorable environment for emergence of pathogen virulence and development of serious infections and multiorgan failure. Data to recommend therapies aimed at restoring a disrupted microbiota, such as probiotics/prebiotics and fecal microbiota transplants is currently scarce.

SUMMARY

The microbiome is likely to play an important role in the perioperative and ICU setting but existing data is largely descriptive. There is an expanding number of mechanistic studies that attempt to disentangle the complicated bi-directional relationship between the host and the resident microbiota. When these results are combined with ongoing clinical studies, we should be able to offer better therapies aimed at restoring the microbiota in the future.

Current understanding of the gut microbiota shaping mechanisms

Increasing evidences have shown strong associations between gut microbiota and many human diseases, and understanding the dynamic crosstalks of host-microbe interaction in the gut has become necessary for the detection, prevention, or therapy of diseases. Many reports have showed that diet, nutrient, pharmacologic factors and many other stimuli play dominant roles in the modulation of gut microbial compositions. However, it is inappropriate to neglect the impact of host factors on shaping the gut microbiota. In this review, we highlighted the current findings of the host factors that could modulate the gut microbiota. Particularly the epithelium-associated factors, including the innate immune sensors, anti-microbial peptides, mucus barrier, secretory IgAs, epithelial microvilli, epithelial tight junctions, epithelium metabolism, oxygen barrier, and even the microRNAs are discussed in the context of the microbiota shaping. With these shaping factors, the gut epithelial cells could select the residing microbes and affect the microbial composition. This knowledge not only could provide the opportunities to better control many diseases, but may also be used for predicting the success of fecal microbiota transplantation clinically.

Gut Microbiota as a Therapeutic Target to Ameliorate the Biochemical, Neuroanatomical, and Behavioral Effects of Traumatic Brain Injuries

Current efficacious treatments for traumatic brain injury (TBI) are lacking. Establishment of a protective gut microbiota population offers a compelling therapeutic avenue, as brain injury induces disruptions in the composition of the gut microbiota, i.e., gut dysbiosis, which has been shown to contribute to TBI-related neuropathology and impaired behavioral outcomes. The gut microbiome is involved in the modulation of a multitude of cellular and molecular processes fundamental to the progression of TBI-induced pathologies including neuroinflammation, blood brain barrier permeability, immune system response, microglial activation, and mitochondrial dysfunction, as well as intestinal motility and permeability. Additionally, gut dysbiosis further aggravates behavioral impairments in animal models of TBI and spinal cord injury, as well as negatively affects health outcomes in murine stroke models. Recent studies indicate that microbiota transplants and probiotics ameliorate neuroanatomical damage and functional impairments in animal models of stroke and spinal cord injury. In addition, probiotics have been shown to reduce the rate of infection and time spent in intensive care of hospitalized patients suffering from brain trauma. Perturbations in the composition of the gut microbiota and its metabolite profile may also serve as potential diagnostic and theragnostic biomarkers for injury severity and progression. This review aims to address the etiological role of the gut microbiome in the biochemical, neuroanatomical, and behavioral/cognitive consequences of TBI, as well as explore the potential of gut microbiome manipulation in the form of probiotics as an effective therapeutic to ameliorate TBI-induced pathology and symptoms.

Adverse Reactions to Wheat or Wheat Components

Wheat is an important staple food globally, providing a significant contribution to daily energy, fiber, and micronutrient intake. Observational evidence for health impacts of consuming more whole grains, among which wheat is a major contributor, points to significant risk reduction for diabetes, cardiovascular disease, and colon cancer. However, specific wheat components may also elicit adverse physical reactions in susceptible individuals such as celiac disease (CD) and wheat allergy (WA). Recently, broad coverage in the popular and social media has suggested that wheat consumption leads to a wide range of adverse health effects. This has motivated many consumers to avoid or reduce their consumption of foods that contain wheat/gluten, despite the absence of diagnosed CD or WA, raising questions about underlying mechanisms and possible nocebo effects. However, recent studies did show that some individuals may suffer from adverse reactions in absence of CD and WA. This condition is called non-celiac gluten sensitivity (NCGS) or non-celiac wheat sensitivity (NCWS). In addition to gluten, wheat and derived products contain many other components which may trigger symptoms, including inhibitors of α-amylase and trypsin (ATIs), lectins, and rapidly fermentable carbohydrates (FODMAPs). Furthermore, the way in which foods are being processed, such as the use of yeast or sourdough fermentation, fermentation time and baking conditions, may also affect the presence and bioactivity of these components. The present review systematically describes the characteristics of wheat-related intolerances, including their etiology, prevalence, the components responsible, diagnosis, and strategies to reduce adverse reactions.

The Sleep-Immune Crosstalk in Health and Disease

Sleep and immunity are bidirectionally linked. Immune system activation alters sleep, and sleep in turn affects the innate and adaptive arm of our body's defense system. Stimulation of the immune system by microbial challenges triggers an inflammatory response, which, depending on its magnitude and time course, can induce an increase in sleep duration and intensity, but also a disruption of sleep. Enhancement of sleep during an infection is assumed to feedback to the immune system to promote host defense. Indeed, sleep affects various immune parameters, is associated with a reduced infection risk, and can improve infection outcome and vaccination responses. The induction of a hormonal constellation that supports immune functions is one likely mechanism underlying the immune-supporting effects of sleep. In the absence of an infectious challenge, sleep appears to promote inflammatory homeostasis through effects on several inflammatory mediators, such as cytokines. This notion is supported by findings that prolonged sleep deficiency (e.g., short sleep duration, sleep disturbance) can lead to chronic, systemic low-grade inflammation and is associated with various diseases that have an inflammatory component, like diabetes, atherosclerosis, and neurodegeneration. Here, we review available data on this regulatory sleep-immune crosstalk, point out methodological challenges, and suggest questions open for future research.

Crosstalk between the Ketogenic Diet and Epilepsy: From the Perspective of Gut Microbiota

Given the association between a range of neurological disorders and changes in the gut microbiota, interest in the gut microbiota has recently increased. In particular, the significant involvement of the autoimmune processes in the development of epilepsy, one of the most serious and widespread neurological diseases, has led to a suggested link with the gut microbiome. Because the constitution of the gut microbiome can be influenced by diet, dietary therapy has been shown to have a positive impact on a wide range of conditions via alteration of the gut microbiota. An example of one such diet is the ketogenic diet (KD), which promotes a diet that contains high levels of fat, adequate levels of protein, and low levels of carbohydrate. Due to the near-total elimination of carbohydrates from the individual's food in this ultra-high-fat diet, ketone bodies become an important source of energy. Although the ketogenic diet has proven successful in the treatment of refractory epilepsy and other illnesses, the underlying mechanisms of its neuroprotective effects have yet to be fully elucidated. Nevertheless, recent studies strongly indicate a role for the gut microbiota in the effective treatment of epilepsy with the ketogenic diet. The latest advances regarding the links between the ketogenic diet, gut microbiota, and epilepsy are reviewed in this article, with a particular focus on the role of the gut microbiota in the treatment outcome.

Bidirectional association between migraine and fibromyalgia: retrospective cohort analyses of two populations

OBJECTIVE

Fibromyalgia (FM) and migraine are common pain disorders that tend to coexist. This study determined whether these two conditions exhibited any mutual influences.

SETTING

Cohort study.

PARTICIPANTS

A retrospective, longitudinal cohort study was conducted using data obtained from a nationwide healthcare database. This study had two arms. Arm 1 comprised 33 216 patients with FM and arm 2 consisted of 7420 patients with migraine; all of these patients were diagnosed between 2000 and 2010. Using the aforementioned database, control subjects who had neither FM nor migraine and were matched with the FM and migraine patients by sex, age and index date of diagnosis were recruited. Each control cohort was four times the size of the corresponding study cohort. Follow-up for the control and study cohorts was conducted until the end of 2011.

RESULTS

The incidence rates of FM and migraine were calculated in arms 1 and 2, respectively. The overall incidence of migraine was greater in the FM cohort than in the corresponding control cohort (4.39 vs 2.07 per 1000 person-years (PY)); crude HR=2.12, 95% CI=1.96 to 2.30; adjusted HR (aHR)=1.89, 95% CI=1.75 to 2.05). After adjustment for sex, age and comorbidities, the overall incidence of FM in the migraine cohort was 1.57 times greater than that in the corresponding control cohort (7.01 vs 4.49 per 1000 PY; aHR=1.52, 95% CI=1.39 to 1.65).

CONCLUSIONS

The present study revealed a bidirectional link between FM and migraine.

Effect of probiotic interventions on depressive symptoms: A narrative review evaluating systematic reviews

Depression is one of the most prevalent mental illnesses and is often associated with various other medical disorders. Since the 1980s, the primary pharmacological treatment has been antidepressants, but due to the recent discovery of the association between the gut microbiome and mental health, probiotics have been proposed as an adjunctive or alternate treatment. In this narrative review, we aim to provide a holistic perspective by synthesizing and evaluating existing evidence, discussing key biological mechanisms, exploring the history of probiotic use, and appreciating the influence of modern diet on mental health. Five online databases were searched for relevant studies up to December 2017. Systematic reviews that included randomized controlled trials assessing the efficacy of probiotics in the treatment of depressive symptoms were included. Seven systematic reviews met the inclusion criteria. Three of these reviews conducted meta-analyses, out of which, two concluded that probiotics improved depressive symptoms in the sample population. Out of the four reviews that conducted qualitative analysis, three reviews concluded that probiotics have the potential to be used as a treatment. Due to the differences in clinical trials, a definitive effect of probiotics on depressive symptoms cannot be concluded. Nonetheless, probiotics seem to potentially produce a significant therapeutic effect for subjects with pre-existing depressive symptoms. Further studies are warranted for definitive conclusions.

Nutrients in Alzheimer’s Disease: The Interaction of Diet, Drugs and Disease

In recent decades, clinical trials in Alzheimer’s disease (AD) have failed at an unprecedented rate. The etiology of AD has since come under renewed scrutiny, both to elucidate the underlying pathologies and to identify novel therapeutic strategies. Here, diet has emerged as a potential causative/protective agent. A variety of nutrients, including lipids, minerals, vitamins, antioxidants and sugars as well as broader dietary patterns and microbiotal interactions have demonstrated associations with AD. Although clinical trials have yet to definitively implicate any singular dietary element as therapeutic or causative, it is apparent that dietary preferences, likely in complex synergies, may influence the risk, onset and course of AD. This review catalogs the impact of major dietary elements on AD. It further examines an unexplored reciprocal association where AD may modulate diet, as well as how potential therapeutics may complicate these interactions. In doing so, we observe diet may have profound effects on the outcome of a clinical trial, either as a confounder of a drug/disease interaction or as a generally disruptive covariate. We therefore conclude that future clinical trials in AD should endeavor to control for diet, either in study design or subsequent analyses.

Heat-killed lactobacilli alter both microbiota composition and behaviour

Recently it has been proposed to expand the definition of psychobiotics (beneficial bacteria (probiotics) or support for such bacteria (prebiotics) that positively impact mental health) to any exogenous influence whose effect on the brain is bacterially-mediated. This definition would include inactivated microorganisms with anxiolytic and antidepressant effects. The use of inactivated microorganisms has several advantages over living organisms, including no risk of infection in vulnerable individuals and ease of use in terms of storage and delivery options. It has been reported that consumption of inactivated microorganisms can affect behaviour, particularly in chronic or prolonged stress situations, but effects on healthy populations have not been investigated to the same extent. Also, only limited data is available on the effects of inactivated microorganisms on the microbiota of healthy individuals (animal or human). Therefore, we investigated the effect of feeding a standard mouse chow which incorporates ADR-159, a heat-killed fermentate generated by two Lactobacillus strains, on the behaviour and microbiota of healthy mice. Prolonged consumption of ADR-159 diet had no adverse effect on anthropometrics or general health, but the ADR-159 fed animals demonstrated increased sociability and lower baseline corticosterone levels (stress hormone). The diet also led to subtle but significant changes in the microbiota, with less abundant taxa being most affected. The behavioural, biochemical and microbiological results provide a new light on the impact of inactivated microorganisms and their metabolites on the social behaviour and microbiota of healthy mice.

Gut-Brain Psychology: Rethinking Psychology From the Microbiota-Gut-Brain Axis

Mental disorders and neurological diseases are becoming a rapidly increasing medical burden. Although extensive studies have been conducted, the progress in developing effective therapies for these diseases has still been slow. The current dilemma reminds us that the human being is a superorganism. Only when we take the human self and its partner microbiota into consideration at the same time, can we better understand these diseases. Over the last few centuries, the partner microbiota has experienced tremendous change, much more than human genes, because of the modern transformations in diet, lifestyle, medical care, and so on, parallel to the modern epidemiological transition. Existing research indicates that gut microbiota plays an important role in this transition. According to gut-brain psychology, the gut microbiota is a crucial part of the gut-brain network, and it communicates with the brain via the microbiota-gut-brain axis. The gut microbiota almost develops synchronously with the gut-brain, brain, and mind. The gut microbiota influences various normal mental processes and mental phenomena, and is involved in the pathophysiology of numerous mental and neurological diseases. Targeting the microbiota in therapy for these diseases is a promising approach that is supported by three theories: the gut microbiota hypothesis, the "old friend" hypothesis, and the leaky gut theory. The effects of gut microbiota on the brain and behavior are fulfilled by the microbiota-gut-brain axis, which is mainly composed of the nervous pathway, endocrine pathway, and immune pathway. Undoubtedly, gut-brain psychology will bring great enhancement to psychology, neuroscience, and psychiatry. Various microbiota-improving methods including fecal microbiota transplantation, probiotics, prebiotics, a healthy diet, and healthy lifestyle have shown the capability to promote the function of the gut-brain, microbiota-gut-brain axis, and brain. It will be possible to harness the gut microbiota to improve brain and mental health and prevent and treat related diseases in the future.

Butyrate and Dietary Soluble Fiber Improve Neuroinflammation Associated With Aging in Mice

Aging results in chronic systemic inflammation that can alter neuroinflammation of the brain. Specifically, microglia shift to a pro-inflammatory phenotype predisposing them to hyperactivation upon stimulation by peripheral immune signals. It is proposed that certain nutrients can delay brain aging by preventing or reversing microglial hyperactivation. Butyrate, a short-chain fatty acid (SCFA) produced primarily by bacterial fermentation of fiber in the colon, has been extensively studied pharmacologically as a histone deacetylase inhibitor and serves as an attractive therapeutic candidate, as butyrate has also been shown to be anti-inflammatory and improve memory in animal models. In this study, we demonstrate that butyrate can attenuate pro-inflammatory cytokine expression in microglia in aged mice. It is still not fully understood, however, if an increase in butyrate-producing bacteria in the gut as a consequence of a diet high in soluble fiber could affect microglial activation during aging. Adult and aged mice were fed either a 1% cellulose (low fiber) or 5% inulin (high fiber) diet for 4 weeks. Findings indicate that mice fed inulin had an altered gut microbiome and increased butyrate, acetate, and total SCFA production. In addition, histological scoring of the distal colon demonstrated that aged animals on the low fiber diet had increased inflammatory infiltrate that was significantly reduced in animals consuming the high fiber diet. Furthermore, gene expression of inflammatory markers, epigenetic regulators, and the microglial sensory apparatus (i.e., the sensome) were altered by both diet and age, with aged animals exhibiting a more anti-inflammatory microglial profile on the high fiber diet. Taken together, high fiber supplementation in aging is a non-invasive strategy to increase butyrate levels, and these data suggest that an increase in butyrate through added soluble fiber such as inulin could counterbalance the age-related microbiota dysbiosis, potentially leading to neurological benefits.

Systematic review with meta-analysis: online psychological interventions for mental and physical health outcomes in gastrointestinal disorders including irritable bowel syndrome and inflammatory bowel disease

BACKGROUND

Online psychotherapy has been successfully used as supportive treatment in many chronic illnesses. However, there is a lack of evidence on its role in the management of gastrointestinal (GI) diseases.

AIMS

To examine whether online psychological interventions improve mental and physical outcomes in gastrointestinal diseases.

METHODS

We searched CINAHL Plus, MEDLINE, EMBASE, Health Management Information Consortium, PsycINFO, British Nursing Index, Cochrane Library, a specialised register of the IBD/FBD Cochrane Group, MEDLINE (PubMed) WHO International Clinical Trial Registry, ClinicalTrials.gov, and reference lists of all papers included in the review. The Cochrane Risk of Bias Tool was used to assess internal validity. Where possible, data were pooled using random-effects meta-analysis.

RESULTS

We identified 11 publications (encompassing nine studies) meeting inclusion criteria. One study had a high risk of selection bias (allocation concealment), all studies had a high risk of performance and detection bias. Eight studies were included in the meta-analyses (6 on irritable bowel syndrome [IBS] and two on inflammatory bowel disease [IBD]). Online cognitive behavioural therapy (CBT) was shown to significantly improve gastrointestinal symptom-specific anxiety (MD: -8.51, 95% CI -12.99 to -4.04, P = 0.0002) and lessen symptom-induced disability (MD: -2.78, 95% CI -5.43 to -0.12, P = 0.04) in IBS post intervention. There was no significant effect of online CBT on any other outcomes in IBS. No significant effect of online psychotherapy was demonstrated in IBD.

CONCLUSION

There is insufficient evidence to demonstrate the effectiveness of online CBT to manage mental and physical outcomes in gastrointestinal diseases.

The interaction between invariant Natural Killer T cells and the mucosal microbiota

The surface of mammalian bodies is colonized by a multitude of microbial organisms, which under normal conditions support the host and are considered beneficial commensals. This requires, however, that the composition of the commensal microbiota is tightly controlled and regulated. The host immune system plays an important role in the maintenance of this microbiota composition. Here we focus on the contribution of one particular immune cell type, invariant Natural Killer T (iNKT) cells, in this process. The iNKT cells are a unique subset of T cells characterized by two main features. First, they express an invariant T-cell receptor that recognizes glycolipid antigens presented by CD1d, a non-polymorphic major histocompatibility complex class I-like molecule. Second, iNKT cells develop as effector/memory cells and swiftly exert effector functions, like cytokine production and cytotoxicity, after activation. We outline the influence that the mucosal microbiota can have on iNKT cells, and how iNKT cells contribute to the maintenance of the microbiota composition.

Brain, antibiotics, and microbiota - how do they interplay?: An Editorial for 'Antibiotics-induced modulation of large intestinal microbiota altered aromatic amino acid profile and expression of neurotransmitters in the hypothalamus of piglets' on page 219

The microbiome and its cross-talk with the brain have drawn increasing attention lately, since imbalances in the gut microbiota's composition may result in pathogenic dysfunctions affecting brain functioning up to development of neurodegenerative and mental diseases. The current Editorial discusses a study by Gao and coworkers in the current issue of the Journal of Neurochemistry in which the authors use a model of antibiotic-induced dysbiosis - targeted infusion of antibiotics into the gut - to assess if microbiotic metabolites exert effects on local neurotransmitter expression or contribute to the gut-brain axis. The authors mechanistically link distal ileal infusion of antibiotics with a change in the levels of microbial metabolites that affect the expression of neurotransmitters in the brain and thereby can participate in the fine-tuning of the hypothalamic functions, including regulation of visceral and neuroendocrine processes, stress responses, mood and anxiety. Their study thus represents an important step towards our understanding of the brain-gut axis, with the potential to advance therapeutics.

A Review of Traumatic Brain Injury and the Gut Microbiome: Insights into Novel Mechanisms of Secondary Brain Injury and Promising Targets for Neuroprotection

The gut microbiome and its role in health and disease have recently been major focus areas of research. In this review, we summarize the different ways in which the gut microbiome interacts with the rest of the body, with focus areas on its relationships with immunity, the brain, and injury. The gut–brain axis, a communication network linking together the central and enteric nervous systems, represents a key bidirectional pathway with feed-forward and feedback mechanisms. The gut microbiota has a central role in this pathway and is significantly altered following injury, leading to a pro-inflammatory state within the central nervous system (CNS). Herein, we examine traumatic brain injury (TBI) in relation to this axis and explore potential interventions, which may serve as targets for improving clinical outcomes and preventing secondary brain injury.

Core versus diet-associated and postprandial bacterial communities of the rainbow trout (Oncorhynchus mykiss) midgut and faeces

This study investigated the impact of different dietary ingredients, with different protein/lipid sources, on midgut and faeces bacteria community structures just before feeding and 3 h after feeding a single meal to individual rainbow trout (Oncorhynchus mykiss). Fish were kept in experimental rearing facilities and fed ad libitum twice daily for 5 weeks. Fish were fed three different commercial diets, which contained variations of high or low marine fishmeal/fish oil content. DNA was extracted from midgut and faeces samples for analysis of their bacterial 16S rRNA gene diversity by targeting the V3-V4 region with 454 pyrosequencing. A total of 332 unique bacterial operational taxonomic units (OTUs) were revealed in all samples. However, each sample was dominated (>80% relative abundance) by 2–14 OTUs, with the single most dominant OTU having >30% dominance, indicating that only a few bacteria were fundamental in terms of relative abundance in each treatment. Fifteen OTUs occurred in all samples (core microbiota). The majority of these OTUs belonged to the Proteobacteria, Firmicutes or Tenericutes, and were associated with other animal gut environments. The faecal material and the midgut samples had few overlaps in their shared OTUs. A postprandial response in the gut bacterial community structure 3 h after feeding highlights how dietary stimulation induces structural changes in the microbiota profiles in the established gut bacteria. This study showed that feeding O. mykiss different diets and even single meals lead to perturbations in the established gut bacteria of O. mykiss.

Summary: The gut bacterial microbiome of rainbow trout contains a few core bacterial taxa and has little overlap with its faeces. Bacterial communities can change even 3 h after feeding.

Recognizing Depression from the Microbiota⁻Gut⁻Brain Axis

Major depression is one of the leading causes of disability, morbidity, and mortality worldwide. The brain⁻gut axis functions are disturbed, revealed by a dysfunction of the brain, immune system, endocrine system, and gut. Traditional depression treatments all target the brain, with different drugs and/or psychotherapy. Unfortunately, most of the patients have never received any treatment. Studies indicate that gut microbiota could be a direct cause for the disorder. Abnormal microbiota and the microbiota⁻gut⁻brain dysfunction may cause mental disorders, while correcting these disturbance could alleviate depression. Nowadays, the gut microbiota modulation has become a hot topic in treatment research of mental disorders. Depression is closely related with the health condition of the brain⁻gut axis, and maintaining/restoring the normal condition of gut microbiota helps in the prevention/therapy of mental disorders.

From the Bottom-Up: Chemotherapy and Gut-Brain Axis Dysregulation

The central nervous system and gastrointestinal tract form the primary targets of chemotherapy-induced toxicities. Symptoms associated with damage to these regions have been clinically termed chemotherapy-induced cognitive impairment and mucositis. Whilst extensive literature outlines the complex etiology of each pathology, to date neither chemotherapy-induced side-effect has considered the potential impact of one on the pathogenesis of the other disorder. This is surprising considering the close bidirectional relationship shared between each organ; the gut-brain axis. There are complex multiple pathways linking the gut to the brain and vice versa in both normal physiological function and disease. For instance, psychological and social factors influence motility and digestive function, symptom perception, and behaviors associated with illness and pathological outcomes. On the other hand, visceral pain affects central nociception pathways, mood and behavior. Recent interest highlights the influence of functional gut disorders, such as inflammatory bowel diseases and irritable bowel syndrome in the development of central comorbidities. Gut-brain axis dysfunction and microbiota dysbiosis have served as key portals in understanding the potential mechanisms associated with these functional gut disorders and their effects on cognition. In this review we will present the role gut-brain axis dysregulation plays in the chemotherapy setting, highlighting peripheral-to-central immune signaling mechanisms and their contribution to neuroimmunological changes associated with chemotherapy exposure. Here, we hypothesize that dysregulation of the gut-brain axis plays a major role in the intestinal, psychological and neurological complications following chemotherapy. We pay particular attention to evidence surrounding microbiota dysbiosis, the role of intestinal permeability, damage to nerves of the enteric and peripheral nervous systems and vagal and humoral mediated changes.

Circadian Disruption Changes Gut Microbiome Taxa and Functional Gene Composition

Disrupted circadian rhythms and alterations of the gut microbiome composition were proposed to affect host health. Therefore, the aim of this research was to identify whether these events are connected and if circadian rhythm disruption by abnormal light–dark (LD) cycles affects microbial community gene expression and host vulnerability to intestinal dysfunction. Mice were subjected to either a 4-week period of constant 24-h light or of normal 12-h LD cycles. Stool samples were collected at the beginning and after the circadian rhythm disruption. A metatranscriptomic analysis revealed an increase in Ruminococcus torques, a bacterial species known to decrease gut barrier integrity, and a decrease in Lactobacillus johnsonii, a bacterium that helps maintain the intestinal epithelial cell layer, after circadian rhythm disruption. In addition, genes involved in pathways promoting host beneficial immune responses were downregulated, while genes involved in the synthesis and transportation of the endotoxin lipopolysaccharide were upregulated in mice with disrupted circadian cycles. Importantly, these mice were also more prone to dysfunction of the intestinal barrier. These results further elucidate the impact of light-cycle disruption on the gut microbiome and its connection with increased incidence of disease in response to circadian rhythm disturbances.

Supplementation of amylase combined with glucoamylase or protease changes intestinal microbiota diversity and benefits for broilers fed a diet of newly harvested corn

Background

The effect of amylases combined with exogenous carbohydrase and protease in a newly harvested corn diet on starch digestibility, intestine health and cecal microbiota was investigated in broiler chickens.

Methods

Two hunderd and eighty-eight 5-day-old female chickens were randomly divided into six treatments: a newly harvested corn-soybean meal diet (control); control supplemented with 1,500 U/g α-amylase (Enzyme A); Enzyme A + 300 U/g amylopectase + 20,000 U/g glucoamylase (Enzyme B); Enzyme B + protease 10,000 U/g (Enzyme C); Enzyme C + xylanase 15,000 U/g (Enzyme D); and Enzyme D + cellulase 200 U/g + pectinase 1,000 U/g (Enzyme E). Growth performance, starch digestibility, digestive organ morphology, and intestinal microbiota were evaluated in the birds at 16 and 23 d of age.

Results

Compared with the control diet, supplementation with Enzyme A significantly decreased ileum lesion scoring at 16 d of age (P < 0.05); supplementation with Enzyme B or Enzyme C showed positive effects on ileal amylopectin and total starch digestibility (P < 0.05); Broilers fed with a diet supplemented with Enzyme D had a tendency to decrease body weight gain at 23 d. Enzyme E supplementation improved lesion scoring of jejunum and ileum at 16 d (P < 0.05), and increased ileal amylopectin or total starch digestibility at 23 d (P < 0.05). Supplementation of enzymes changed cecal microbiota diversity. High numbers of Campylobacter, Helicobacter and Butyricicoccus, Anaerostipes and Bifidobacterium, Sutterella and Odoribacter were the main genera detected in supplementations with Enzymes B, C, D, and E respectively.

Conclusions

Supplementation with amylase combined with glucoamylase or protease showed a beneficial effect on starch digestibility and intestinal microbiota diversity, and increased growth of broilers fed with newly harvested corn.

Complex interactions of circadian rhythms, eating behaviors, and the gastrointestinal microbiota and their potential impact on health

Human health is intricately intertwined with the composition and function of the trillions of microorganisms that make up the gastrointestinal (GI) microbiome. The GI microbiome is essentially a microbial organ that provides metabolic, immunologic, and protective functions for the host. Habitual diet, changes in macronutrient composition, and consumption of nondigestible dietary fibers have all been shown to impact the human GI microbiome. Intriguingly, the impact of diet on the microbiome may be related not only to what humans eat but also to the timing of food consumption. Emerging preclinical research suggests that gut microbes experience diurnal rhythms, and the health effects of eating patterns, including time-restricted feeding and meal frequency, may be related to the GI microbiome. Herein, the complex connections among circadian rhythms, eating behaviors, the GI microbiome, and health are reviewed, highlighting the need for additional translational research in this area.

Gut Microbiota: An Integral Moderator in Health and Disease

The gut microbiota, as the main member in gut microecology, is an essential mediator in health and disease. The gut microbiota interacts with various organs and systems in the body, including brain, lung, liver, bone, cardiovascular system, and others. Microbiota-derived metabolites such as the short chain fatty acid (SCFA) butyrate are primary signals, which link the gut microbiota and physiology. Recently, the gut microbiota has been identified as the origin of a number of diseases by influencing the related cell signaling pathways such as WNT/beta-catenin pathway in colorectal cancer and T cell receptor signaling in the central nervous system. Moreover, several microRNAs participate in signaling networks through the intervention of the gut microbiota. The interaction between the gut microbiota and miRNAs plays a crucial role in vascular dysfunction and hepatocellular carcinoma (HCC). In this review, we will report and discuss recent findings about the crosstalk between the gut microbiota and physical organs and how the gut microbiota and miRNAs regulate each other while influencing the host via genes, proteins, or metabolites.

The IMPROVE Guidelines (Ischaemia Models: Procedural Refinements Of in Vivo Experiments)

Most in vivo models of ischaemic stroke target the middle cerebral artery and a spectrum of stroke severities, from mild to substantial, can be achieved. This review describes opportunities to improve the in vivo modelling of ischaemic stroke and animal welfare. It provides a number of recommendations to minimise the level of severity in the most common rodent models of middle cerebral artery occlusion, while sustaining or improving the scientific outcomes. The recommendations cover basic requirements pre-surgery, selecting the most appropriate anaesthetic and analgesic regimen, as well as intraoperative and post-operative care. The aim is to provide support for researchers and animal care staff to refine their procedures and practices, and implement small incremental changes to improve the welfare of the animals used and to answer the scientific question under investigation. All recommendations are recapitulated in a summary poster (see supplementary information).

Environmental Pollutant Benzo[a]Pyrene Impacts the Volatile Metabolome and Transcriptome of the Human Gut Microbiota

Benzo[a]pyrene (B[a]P) is a ubiquitous, persistent, and carcinogenic pollutant that belongs to the large family of polycyclic aromatic hydrocarbons. Population exposure primarily occurs via contaminated food products, which introduces the pollutant to the digestive tract. Although the metabolism of B[a]P by host cells is well known, its impacts on the human gut microbiota, which plays a key role in health and disease, remain unexplored. We performed an in vitro assay using 16S barcoding, metatranscriptomics and volatile metabolomics to study the impact of B[a]P on two distinct human fecal microbiota. B[a]P exposure did not induce a significant change in the microbial structure; however, it altered the microbial volatolome in a dose-dependent manner. The transcript levels related to several metabolic pathways, such as vitamin and cofactor metabolism, cell wall compound metabolism, DNA repair and replication systems, and aromatic compound metabolism, were upregulated, whereas the transcript levels related to the glycolysis-gluconeogenesis pathway and bacterial chemotaxis toward simple carbohydrates were downregulated. These primary findings show that food pollutants, such as B[a]P, alter human gut microbiota activity. The observed shift in the volatolome demonstrates that B[a]P induces a specific deviation in the microbial metabolism.

Cell-Surface and Nuclear Receptors in the Colon as Targets for Bacterial Metabolites and Its Relevance to Colon Health

The symbiotic co-habitation of bacteria in the host colon is mutually beneficial to both partners. While the host provides the place and food for the bacteria to colonize and live, the bacteria in turn help the host in energy and nutritional homeostasis, development and maturation of the mucosal immune system, and protection against inflammation and carcinogenesis. In this review, we highlight the molecular mediators of the effective communication between the bacteria and the host, focusing on selective metabolites from the bacteria that serve as messengers to the host by acting through selective receptors in the host colon. These bacterial metabolites include the short-chain fatty acids acetate, propionate, and butyrate, the tryptophan degradation products indole-3-aldehyde, indole-3-acetic, acid and indole-3-propionic acid, and derivatives of endogenous bile acids. The targets for these bacterial products in the host include the cell-surface G-protein-coupled receptors GPR41, GPR43, and GPR109A and the nuclear receptors aryl hydrocarbon receptor (AhR), pregnane X receptor (PXR), and farnesoid X receptor (FXR). The chemical communication between these bacterial metabolite messengers and the host targets collectively has the ability to impact metabolism, gene expression, and epigenetics in colonic epithelial cells as well as in mucosal immune cells. The end result, for the most part, is the maintenance of optimal colonic health.

Organotypic cultures of cerebellar slices as a model to investigate demyelinating disorders

INTRODUCTION

Demyelinating disorders, characterized by a chronic or episodic destruction of the myelin sheath, are a leading cause of neurological disability in young adults in western countries. Studying the complex mechanisms involved in axon myelination, demyelination and remyelination requires an experimental model preserving the neuronal networks and neuro-glial interactions. Organotypic cerebellar slice cultures appear to be the best alternative to in vivo experiments and the most commonly used model for investigating etiology or novel therapeutic strategies in multiple sclerosis. Areas covered: This review gives an overview of slice culture techniques and focuses on the use of organotypic cerebellar slice cultures on semi-permeable membranes for studying many aspects of axon myelination and cerebellar functions. Expert opinion: Cerebellar slice cultures are probably the easiest way to faithfully reproduce all stages of axon myelination/demyelination/remyelination in a three-dimensional neuronal network. However, in the cerebellum, neurological disability in multiple sclerosis also results from channelopathies which induce changes in Purkinje cell excitability. Cerebellar cultures offer easy access to electrophysiological approaches which are largely untapped and we believe that these cultures might be of great interest when studying changes in neuronal excitability, axonal conduction or synaptic properties that likely occur during multiple sclerosis.

Human Gut Microbiota: Toward an Ecology of Disease

Composed of trillions of individual microbes, the human gut microbiota has adapted to the uniquely diverse environments found in the human intestine. Quickly responding to the variances in the ingested food, the microbiota interacts with the host via reciprocal biochemical signaling to coordinate the exchange of nutrients and proper immune function. Host and microbiota function as a unit which guards its balance against invasion by potential pathogens and which undergoes natural selection. Disturbance of the microbiota composition, or dysbiosis, is often associated with human disease, indicating that, while there seems to be no unique optimal composition of the gut microbiota, a balanced community is crucial for human health. Emerging knowledge of the ecology of the microbiota-host synergy will have an impact on how we implement antibiotic treatment in therapeutics and prophylaxis and how we will consider alternative strategies of global remodeling of the microbiota such as fecal transplants. Here we examine the microbiota-human host relationship from the perspective of the microbial community dynamics.

Gut Microbiota: A Potential Regulator of Neurodevelopment

During childhood, our brain is exposed to a variety of environmental inputs that can sculpt synaptic connections and neuronal circuits, with subsequent influence on behavior and learning processes. Critical periods of neurodevelopment are windows of opportunity in which the neuronal circuits are extremely plastic and can be easily subjected to remodeling in response to experience. However, the brain is also more susceptible to aberrant stimuli that might lead to altered developmental trajectories. Intriguingly, postnatal brain development is paralleled by the maturation of the gut microbiota: the ecosystem of symbionts populating our gastro-intestinal tract. Recent discoveries have started to unveil an unexpected link between the gut microbiome and neurophysiological processes. Indeed, the commensal bacteria seem to be able to influence host behavioral outcome and neurochemistry through mechanisms which remain poorly understood. Remarkably, the efficacy of the gut flora action appears to be dependent on the timing during postnatal life at which the host gut microbes’ signals reaches the brain, suggesting the fascinating possibility of critical periods for this microbiota-driven shaping of host neuronal functions and behavior. Therefore, to understand the importance of the intestinal ecosystem’s impact on neuronal circuits functions and plasticity during development and the discovery of the involved molecular mechanisms, will pave the way to identify new and, hopefully, powerful microbiota-based therapeutic interventions for the treatment of neurodevelopmental and psychiatric diseases.

"I Am I and My Bacterial Circumstances": Linking Gut Microbiome, Neurodevelopment, and Depression

Recently, there has been renewed interest in the role played by microbiome in both human health and human disease. A correct equilibrium between the human host and their microorganisms is important for an appropriate physiological function. Extensive research has shown that microbes that inhabit the gastrointestinal tract-or gut microbiota-are involved not only in both nutritive and digestive activities but also in immunological processes. Moreover, the gut microbiome influences both central nervous system and energy homeostasis. An altered gut microbiome has been associated with the pathophysiology of different diseases, including neuropsychiatric disorders. Apparently, both environmental-diet, exposition to antibiotics, and infections-and host-genetic factors have a strong influence on gut microbiome, modulating the risk for neuropsychiatric illness. Also, early life disruption of the microbiome-gut-brain (MGB) axis has been associated with an increased risk of developing depression later in life, suggesting a link between gut microbiome, neurodevelopment, and depression. This review aims to contribute to this growing area of research by exploring the role played by the gut microbiome in neurodevelopment and in the etiology of the depressive syndrome, including nutritional, immunological, and energy homeostasis approaches.

Back to the Basics: Cnidarians Start to Fire

The nervous systems of cnidarians, pre-bilaterian animals that diverged close to the base of the metazoan radiation, are structurally simple and thus have great potential to reveal fundamental principles of neural circuits. Unfortunately, cnidarians have thus far been relatively intractable to electrophysiological and genetic techniques and consequently have been largely passed over by neurobiologists. However, recent advances in molecular and imaging methods are fueling a renaissance of interest in and research into cnidarians nervous systems. Here, we review current knowledge on the nervous systems of cnidarian species and propose that researchers should seize this opportunity and undertake the study of members of this phylum as strategic experimental systems with great basic and translational relevance for neuroscience.

Correlations of Host Genetics and Gut Microbiome Composition

The human gut microbiome has a considerable impact on host health. The long list of microbiome-related health disorders raises the question of what in fact determines microbiome composition. In this review we sought to understand how the host itself impacts the structure of the gut microbiota population, specifically by correlations of host genetics and gut microbiome composition. Host genetic profile has been linked to differences in microbiome composition, thus suggesting that host genetics can shape the gut microbiome of the host. However, cause-consequence mechanisms behind these links are still unclear. A survey of the possible mechanisms allowing host genetics to shape microbiota composition in the gut demonstrated the major role of metabolic functions and the immune system. A considerable impact of other factors, such as diet, may outweigh the effects of host genetic background. More studies are necessary for good understanding of the relations between the host genetic profile, gut microbiome composition, and host health. According to the idea of personalized medicine, patient-tailored management of microbiota content remains a fascinating area for further inquiry.

Effect of Probiotics on Depression: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

It has been reported that gut probiotics play a major role in the bidirectional communication between the gut and the brain. Probiotics may be essential to people with depression, which remains a global health challenge, as depression is a metabolic brain disorder. However, the efficacy of probiotics for depression is controversial. This study aimed to systematically review the existing evidence on the effect of probiotics-based interventions on depression. Randomized, controlled trials, identified through screening multiple databases and grey literature, were included in the meta-analysis. The meta-analysis was performed using Review Manager 5.3 software using a fixed-effects model. The meta-analysis showed that probiotics significantly decreased the depression scale score (MD (depressive disorder) = −0.30, 95% CI (−0.51–−0.09), p = 0.005) in the subjects. Probiotics had an effect on both the healthy population (MD = −0.25, 95% CI (−0.47–−0.03), p = 0.03) and patients with major depressive disorder (MDD) (MD = −0.73, 95% CI (−1.37–−0.09), p = 0.03). Probiotics had an effect on the population aged under 60 (MD = −0.43, 95% CI (−0.72–−0.13), p = 0.005), while it had no effect on people aged over 65 (MD = −0.18, 95% CI (−0.47–0.11), p = 0.22). This is the first systematic review and meta-analysis with the goal of determining the effect of probiotics on depression. We found that probiotics were associated with a significant reduction in depression, underscoring the need for additional research on this potential preventive strategy for depression.

The Gut Mucosal Firewall and Functional Medicine

The evidence is strong: Protection and restoration of the intestinal firewall is of primary importance in many patients suffering from a wide range of chronic diseases. The functional medicine approach to evaluation and treatment of problems associated with compromised integrity of the intestinal firewall represents a successful application of the systems biology approach to the management of chronic disease.

Antibiotic-Induced Changes in the Intestinal Microbiota and Disease

The gut microbiota is a key player in many physiological and pathological processes occurring in humans. Recent investigations suggest that the efficacy of some clinical approaches depends on the action of commensal bacteria. Antibiotics are invaluable weapons to fight infectious diseases. However, by altering the composition and functions of the microbiota, they can also produce long-lasting deleterious effects for the host. The emergence of multidrug-resistant pathogens raises concerns about the common, and at times inappropriate, use of antimicrobial agents. Here we review the most recently discovered connections between host pathophysiology, microbiota, and antibiotics highlighting technological platforms, mechanistic insights, and clinical strategies to enhance resistance to diseases by preserving the beneficial functions of the microbiota.